Cows that are staggering or down are close to being dead cows. A typical beef operation should maintain a less than 1 percent death rate for productive cows. Anything greater should trigger a managerial review to target any potential cause.
The other day, after a nice, wet spring, the alarm went off. Two cows were staggering after a day of sorting and working the cow-calf pairs. Cows shouldn’t stagger, so any indication of instability in a nursing cow is an emergency situation.
The same as having cardiac pads available in human environments, cattle operations should have quick access to a veterinarian for consultation and care in this situation. The two probable causes that came to mind were ketosis (sometimes confused with milk fever at calving) and hypomagnesaemia tetany (commonly called grass tetany or grass staggers). Although there are other metabolic disturbances in cattle, given the setting and time, these two causes came to mind immediately.
Ketosis probably is unlikely because it usually is associated with reduced intake of carbohydrates or more simply, inadequate feed to support the nutritional requirements of a lactating cow. The pastures are adequate but the cows were confined for the work day. Also, there was the added stress of removing cows that had just calved from pasture.
Given the lush forage from recent rains, the more likely problem was grass tetany. Grass tetany must be a concern when the grass is fresh and lush. When the additional demand of lactation is added to the cow, the nutritional requirements and needed absorption of magnesium is critical. Lush grass tends to open the door to an imbalance with other nutritional elements, thus the potential crisis.
The cow initially responds to these metabolic challenges with nervousness and irritability that generally is not apparent to the typical watchful eye. However, due to the rapid onset of the problem, even in well-managed cows, a quick response and treatment is critical. The involuntary contraction of muscles caused by tetany is noticeable to the astute eye, especially when cattle are moved.
Even when challenging a cow to get out of the way, any sign of slight staggering should bring an immediate response when conditions for grass tetany are right. Again, be on high alert when dealing with lush grass, calving, high-milking cows or any management activities that may add stress to the cows and calves.
The other day, the Dickinson Research Extension Center had all the right conditions for the onset of grass tetany. The center just switched to May calving, so the cows were freshly calved and producing good to excellent milk. Recent rains had produced lush grass, so the cows needed to be sorted and moved to native grass. To further complicate the day, rain prevented the cow-calf pairs from being returned to fresh pasture, so they were fed in the lots and returned to pasture the next morning.